Why?

One day my lovely wife invited to watch youtube videos together. Unfortunately, we don’t have a large screen nor a big TV to watch a video comfortably. In the beginning, we tried to view that on our personal laptop, respectively. To be honest, this is not a good idea. We don’t even know which part we watched in each own notebook. Finally, I remember we might be able to connect two audio outputs at the same time. In this way, we can enjoy together on one laptop.

Given an array of integers, return indices of the two numbers such that they add up to a specific target.You may assume that each input would have exactly one solution, and you may not use the same element twice.